1. Field of the Invention
The present invention relates to a technique for integrating an electronic control unit with an automatic transmission and, more particularly, to a technique for mounting the electronic control unit in an electrically and mechanically connected state on the automatic transmission.
2. Description of the Related Art
As well known in the art, the automatic transmission to be mounted on a vehicle is controlled by operating its hydraulic control apparatus with a shift device and an electronic control unit. This electronic control unit is mounted in a vehicle compartment or an engine room, and a neutral start switch and a position sensor as electric parts for the controls are arranged on the outer side of an automatic transmission case whereas individual sensors for the engine speed or the oil temperature and solenoids are attached, although partially excepted, in the automatic transmission case. Moreover, the electric connections between the individual electric parts and the electronic control unit are effected by a wire harness as the vehicle wiring lines.
As the aforementioned vehicle wiring lines are shown conceptionally and schematically in FIG. 10, more specifically, the wiring lines of various sensors arranged in a transmission housing portion of the transmission case are collected by a wire harness a acting as the in-transmission wiring lines and led to the outside of the transmission case. Wiring lines b of solenoids attached to the valve body in the transmission case are individually led to the outside of the transmission case. Wiring lines d of a neutral switch integrated type position sensor c attached to the outer face of the transmission case wall is connected directly with an electronic control unit f through a wire harness e as the vehicle wiring lines.
With the wiring structure thus far described being adopted, numerous wire harnesses and connectors are required for the electric connections. This necessity makes it difficult to reduce the weight and the cost and raises problems in the large number of mounting design steps and the vehicle assembling steps. Moreover, the automatic transmission body and its electronic control unit are combined when mounted on the vehicle, thereby to make it difficult to manage the quality finely one-to-one while considering the delicate characteristic difference among the individuals. Moreover, the module is made to save the space for the individual arrangements of the various electric parts of the automatic transmission and the electronic control unit so that the space saving is not realized as a whole.